The present invention relates to an apparatus for controlling an elevator and, more particularly, to an apparatus for determining a floor at which an elevator cage can be stopped.
FIG. 6 is a diagram for explaining a method of determining a floor at which an elevator cage can be stopped (hereinafter referred to as an "advance floor") to detect a call of a cage in a cage call selector disclosed, for example, in Japanese Published Unexamined Patent Application No. 57-27877. In the prior art, the advance floor is determined in accordance with interfloor codes produced by encoding interfloor distances and floor detection signals output when a detection switch (limit switch) on a cage engages with cams corresponding to floors provided in an elevator shaft.
More particularly, the advance floor according to a prior-art apparatus is determined two times: immediately after the start and a while after the start. In the former case, time codes are employed, it is determined whether full speed operation is possible by a method to be described later, and, if possible, the advance floor immediately after the start (after 1 sec.) is used as a full speed operation enabling floor. In the latter case, the advance floor is updated by information that a cage has passed cams disposed at the respective floors in the elevator shaft.
A method of determining whether full speed operation is possible will now be described.
In the design of an elevator, the running speed of the cage is preferably set at a value suitable for the running distance. Therefore, the cage is run at a speed lower than a rated speed (hereinafter referred to as a "partial speed") if the running distance is less than a full speed runnable distance corresponding to the rated speed.
In order to determine whether the operating mode should be full speed running or partial speed running, interfloor codes produced by encoding interfloor distances are stored in a read-only memory (ROM), it is detected from which floor a cage starts and at which floor the cage is to be stopped, and whether or not the cage can run at a full speed is judged according to the interfloor code.
The interfloor code is determined as follows in a elevator having, for example, a rated speed of 105 m/min. and a full speed runnable distance of approximately 6000 mm.
When the interfloor distance is less than 3000 mm: interfloor code="00"
When the interfloor distance is more than 3000 mm and less than 6000 mm: interfloor code="01"
When the interfloor distance is more than 6000 mm: interfloor code="02".
Based on the above-described interfloor codes, the operating mode becomes full speed running under the following conditions.
During one-floor operation when an interfloor code is "02",
During two-floor operation when the sum of the interfloor codes is "02" or more, and
During operation over three or more floors (regardless of the interfloor code).
The cage is run at partial speed under all other conditions.
Since the conventional elevator system is constructed as described above, the following problems arise.
(1) Since the operating mode is selected according to the interfloor code, the optimum operating mode is not always selected. One such situation is in an elevator having a rated speed of 105 m/min. in a building having an interfloor distance of 3500 mm between the first and second floors and an interfloor distance of 2700 mm between the second and third floors when the cage is run from the first floor to the third floor. In this case, the distance from the first floor to the third floor is 6200 mm which is greater than the full speed runnable distance. However, since the interfloor codes are respectively "01" and "00", the condition that the sum of the interfloor codes is "02" or more in two floor operation is not satisfied. Thus, the cage can be run only at partial speed irrespective of the full speed runnable distance, so the operating efficiency is decreased.
(2) Since the number of floors and interfloor distances naturally differ from building to building, the interfloor codes to be written in the ROM are different. Thus, ROMs having different contents must be prepared for each building at the time of installing an elevator, complicated labor is required, and modifications are not easy.
(3) Since the cams provided at the respective floors in an elevator shaft are required only for calculating the advance floor and cannot be utilized for other purposes, the economic efficiency is deteriorated, and the installation of the cams requires much labor.